<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="utf-8"/>
    <meta http-equiv="X-UA-Compatible" content="IE=edge,chrome=1"/>
    <meta name="viewport"
          content="width=device-width, initial-scale=1, maximum-scale=1,minimum-scale=1, user-scalable=no">
    <title>dropdown</title>
    <link rel="shortcut icon" href="../img/logo.png" type="image/x-icon"/>
    <link rel="stylesheet" href="../css/bootstrap.css">
    <script src="../js/html5shiv.js"></script>
    <script src="../js/respondjs.js"></script>
    <!-- dropdown组件时要导入popper.js -->
    <script src="../js/popper.js"></script>
    <script src="../js/jquery-3.4.1.js"></script>
    <script src="../js/bootstrap.js"></script>
    <style>
        .dropup {
            position: fixed;
            bottom: 0;
        }
    </style>
</head>
<body>
<div class="container">
    <!-- 下拉组件 -->
    <div class="dropup">
        <div type="button" class="btn btn-primary dropdown-toggle" data-toggle="dropdown" id="menu1">
            下拉 <span class="caret"></span>
        </div>
        <ul class="dropdown-menu" aria-labelledby="menu1" role="menu">
            <li role="presentation">
                <a role="menuitem" tabindex="-1" href="#">Java</a>
            </li>
            <li role="presentation">
                <a role="menuitem" tabindex="-1" href="#">数据挖掘</a>
            </li>
            <li role="presentation">
                <a role="menuitem" tabindex="-1" href="#">数据通信/网络</a>
            </li>
            <!-- 分割线 -->
            <li role="presentation" class="divider"></li>
            <li role="presentation">
                <a role="menuitem" tabindex="-1" href="#">分离的链接</a>
            </li>
        </ul>
    </div>
</div>
</body>
</html>
